Pneumatic tires have a tread pattern in which a plurality of rows of land portions are defined by a plurality of main grooves disposed in a tread portion and extend in the tire circumferential direction (for example, see Japanese Unexamined Patent Application Publication No. 2012-228992). Such pneumatic tires are provided with a plurality of lug grooves extending in the tire lateral direction in each of the land portions in the tread portion and thus ensure excellent drainage performance with the lug grooves.
Unfortunately, if the number of the lug grooves in the tread portion is increased, the rigidity of the tread portion decreases and steering stability on dry road surfaces declines. Conversely, if the number of the lug grooves in the tread portion is decreased, drainage performance decreases and steering stability on wet road surfaces declines. In this way, steering stability on dry road surfaces and steering stability on wet road surfaces have a negative correlation with each other, and it is difficult to enhance both simultaneously.
If the tread portion is subdivided by the main grooves and the lug grooves, the tread portion is susceptible to uneven wear due to nonuniform rigidity. To prevent uneven wear, there are constraints on the arrangement of the main grooves and the lug grooves. Thus, it is more difficult to enhance uneven wear resistance as well as achieving good steering stability on dry road surfaces and steering stability on wet road surfaces in a compatible manner.